Differential Contribution of Transmembrane Domains IV, V, VI, and VII to Human Angiotensin II Type 1 Receptor Homomer Formation

Abstract

G protein-coupled receptors (GPCRs) play an important role in drug therapy and represent one of the largest families of drug targets. The angiotensin II type 1 receptor (AT1R) is notable as it has a central role in the treatment of cardiovascular disease. Blockade of AT1R signaling has been shown to alleviate hypertension and improve outcomes in patients with heart failure. Despite this, it has become apparent that our initial understanding of AT1R signaling is oversimplified. There is considerable evidence to suggest that AT1R signaling is highly modified in the presence of receptor-receptor interactions, but there is very little structural data available to explain this phenomenon even with the recent elucidation of the AT1R crystal structure. The current study investigates the involvement of transmembrane domains in AT1R homomer assembly with the goal of identifying hydrophobic interfaces that contribute to receptor-receptor affinity. A recently published crystal structure of the AT1R was used to guide site-directed mutagenesis of outward-facing hydrophobic residues within the transmembrane region of the AT1R. Bioluminescence resonance energy transfer was employed to analyze how receptor mutation affects the assembly of AT1R homomers with a specific focus on hydrophobic residues. Mutations within transmembrane domains IV, V, VI, and VII had no effect on angiotensin-mediated β-arrestin1 recruitment; however, they exhibited differential effects on the assembly of AT1R into oligomeric complexes. Our results demonstrate the importance of hydrophobic amino acids at the AT1R transmembrane interface and provide the first glimpse of the requirements for AT1R complex assembly.

Interplay Between Angiotensin II Type 1 Receptor and Thrombin Receptor Revealed by Bioluminescence Resonance Energy Transfer Assay

“…physical interaction and homodimerization as previously reported (Hansen et al, 2004;Porrello et al, 2011;Young et al, 2017) and validating our assay. Moreover, a weaker but a significant Rluc signal was also measured in the immunoprecipitate obtained from HA-AT1R/PAR1-Rluc expressing cells ( Figure 9B).…”

Overexpression of ß-Arrestin1 in the Rostral Ventrolateral Medulla Downregulates Angiotensin Receptor and Lowers Blood Pressure in Hypertension

“…β-arrestin1 has long been identified as the protein that regulates GPCRs desensitization, internalization, trafficking and signaling (Ferguson, 2001 ; Gurevich and Gurevich, 2013 ). As a GPCR, AT1R is intimately related to β-arrestin1 function where previous researches mainly focused on the AT1R-mediated β-arrestin1 recruitment and its signaling pathway (Valero et al, 2016 ; Young et al, 2017 ). However, little is known whether β-arrestin1 directly regulates AT1R expression.…”

Novel mechanisms of G-protein-coupled receptors functions: AT1 angiotensin receptor acts as a signaling hub and focal point of receptor cross-talk

“…3D). For instance, several studies have demonstrated that homodimerization has negative allosteric effect on AT 1 R function [84][85][86], and recently the structural requirements of homodimer formation were proposed [87]. In addition, heterodimerization between the mainly G i/o -coupled α 2C AR and G q -coupled AT 1 R was shown to change their G protein preference, and switches to G s proteins and cAMP signaling [77].…”